SHARPENING
The 9/11/07 responses of Hosain Mosavart and Sam Ritter to
Joel Levitt’s question, “How do you sharpen your pictures?”

[The procedures described here can be performed with Photoshop Versions 5 through CS2.  Version CS3 offers additional tools that make sharpening even easier.]

Both Hosain and Sam use Photoshop, and when they process a picture, their first step is to sharpen.  This is because sharpening a boundary between just two colors may not much change the colors, but when three or more colors are involved color changes are likely to be substantial (see Figs.1 thru 3).  Sam also sharpens before printing, but most of his sharpening is done early in the process.

SHARPENING

1. Select the area to be sharpened.  This area may be the entire picture.  And, there are at least two ways to select.
1. Select by color using the Magic Wand Tool.
2. Select using the Polygonal Lasso Tool
2. Hosain's sharpening methods
   1. Sharpen using Hosain’s first method.
      Keying Sequence: Filter>Sharpen>Unsharp Mask>Preview
      (Set Amount and Radius until desired effect is seen).
   2. Sharpen with masking using Hosain’s second method.
      Keying Sequence: Layer>Duplicate Layer>Sharpen the entire picture (See B. a) >Layer>Layer Mask>Hide All>Reveal the areas that needed sharpening by using the Brush Tool to paint those areas with white. (Areas can be concealed by painting them with black.)>Layer>Flatten Image.
3. Sharpening one channel at a time, Sam’s method.
   You can operate on each of ten channels one at a time: seven colors -- each of three in RGB Mode (red, blue and green)
   and each of four in CMYK Mode (Cyan, Magenta, Yellow and Black) and the three LAB channels.
   Keying Sequence: Image>Mode>CMYK or RGB or LAB>Select the color of interest.>Filter>Unsharp Mask (Set the desired Amount and Radius.). Sharpening channel by channel as opposed to other methods often enables more sharpening without the need for much subsequent correction.

Sam recommends: Professional Photoshop: The Classic Guide to Color Correction (5th Edition) by Dan Margulis (Paperback - Nov 20, 2006).  Amazon’s prices are New: $37.79 and Used from $33.00.

 

COLOR CORRECTION

As shown in Figs.1 through 3, sharpening will frequently produce color changes.  Figs.1 & 2 pertain to Hosain’s methods, and Figs. 1 & 3 pertain to Sam’s.  These color changes may consist of changes in the interior of more or less homogeneous areas and/or the production of speckle noise in such areas and/or the production of bounding fringes.  Each can be corrected.

A detailed report of a color adjustment talk presented on 9/11 will be forthcoming shortly.  So, this topic will be treated only cursorily here.

1. Changes in the interior of more or less homogeneous areas and bounding fringes can be corrected in at least three ways.
   1. Select the area to be treated and use the Clone Tool.
   2. Use Replace Color.  Keying Sequence: Image>Adjustments>Replace Color.
   3. Select the area to be treated and use Curves
      Keying Sequence:Image>Adjustments>Curves.
2. Eliminating speckle noise from more or less homogeneous areas can be done in at least two ways. Filter>Blur>Gaussian Blur.
3. Follow Hosain’s second sharpening method using Gaussian Blur instead of Sharpen.